1. Field of the Invention
This invention relates to compression tools and, in particular, a hand operated hydraulic compression tool having an improved relief and release valve.
2. Prior Art
A number of hydraulic compression tools have been developed for providing compression forces, such as about 12 tons of force, for compressing metal connectors about elements, such as wires, to be connected. The tools are generally provided with removable dies for accommodation of different types and sizes of connectors. The tools also conventionally include a pair of handles which are manipulated to provide the high pressure hydraulic piston advance with a control being provided for releasing the pressure upon completion of the connection compression. One type of control is a manual release valve for releasing the hydraulic pressure from a piston cylinder and returning the hydraulic fluid to a reservoir which conventionally may be disposed within one of the operating handles. It is further conventional in such tools to provide overload or pressure relief valves for controlling the maximum pressure applied to the connector to a preselected desired maximum pressure. It has been conventional to form in the body of a compression tool any movable valve member to effect the desired pressure regulation. U.S. Pat. No. 4,226,110 to Suganuma discloses one such hand operated hydraulic compression tool.
A problem exists with hand operated hydraulic compression tools of the prior art in that the tools have separate relief valves and release valves.
A further problem exists with prior art tools in that removal of a relief valve for repair or replacement requires the compression tool to be drained of hydraulic fluid and subsequently refilled with fluid requiring the bleeding of air from the hydraulic conduit system.
A further problem exists with prior art tools in that the separate relief valves and release valves have a relatively large number of parts and seals such as O-rings.
A further problem exists with prior art tools in that maintenance and repair of the tool can be relatively complicated due to the large number of parts and seals.
It is an objective of the present invention to provide a valve for use in a hydraulic compression tool having both manual fluid release capabilities as well as automatic fluid relief capabilities.
It is another objective of the present invention to provide a combined relief/release valve that is self-contained and relatively easy to manufacture.
It is another objective of the present invention to provide a hydraulic compression tool having a relief/release valve that is relatively easy to replace.
It is another objective of the present invention to provide a hydraulic compression tool having a relief/release valve that can have its seals replaced at one procedure.
It is another objective of the present invention to provide a relief/release valve that has relatively few parts.